As disclosed in Japanese Patent Laid-Open No. 2005-353569, for example, there is known a fuel cell system that confines the fuel gas in the fuel cell (referred to as anode dead end system hereinafter). In the anode dead end system, impurities, such as nitrogen and water, are accumulated in the anode gas flow channel of the fuel cell during operation. Thus, the conventional anode dead end system open the exhaust valve at appropriate times to discharge the impurities accumulated in the anode gas flow channel to the outside of the system at the downstream end of the anode.
Patent literature 1: Japanese Patent Laid-Open No. 2005-353569
Patent literature 2: Japanese Patent Laid-Open No. 2005-353303
Patent literature 3: Japanese Patent Laid-Open No. 2005-243477
Patent literature 4: Japanese Patent Laid-Open No. 9-312167